Question

Sin (pi-α) sin(pi/2 + α) / cos²α-1/2

Answer 1

$\frac{sin( \pi - \alpha )sin( \frac{ \pi }{2}- \alpha ) }{cos ^{2} \alpha - \frac{1}{2} }= \frac{2sin \alpha \cdot cos \alpha }{2cos ^{2} \alpha -1 }= \frac{sin2 \alpha }{cos2 \alpha }=tg2 \alpha$

Answer 2

=2sinacosa/(2cos²a-1)=sin2a/cos2a=tg2a